Pathologists typically use microscopes when diagnosing physiological conditions such as cancer, infectious disease and prenatal disorders. Typically, tissue samples on a slide are loaded onto the microscope, the microscope objective or lens focuses on an area of the sample, and the sample is scanned for particular features or objects of interest. In this manner, the microscope helps the pathologist to visually determine the presence of abnormal numbers or types of cells, organelles, organisms or biological markers.
Recently, automated microscopes have been integrated into medical imaging systems that include a variety of networked components. The medical imaging system provides an environment for storing and retrieving the medical images produced by the microscopes. The components of the medical imaging system are spread throughout the department or hospital, or even located remotely, and connected by a communication network.
An image acquisition device is coupled to the microscope and captures images produced by the microscope. The image acquisition device can include a variety of components. For example, the image acquisition device can include a video camera coupled to a high-speed frame grabber for capturing the stream of video produced by the video camera and generating a series of digital images. Alternatively, the electronic camera can be a megapixel digital camera. The microscope and the image acquisition device can acquire images for a number of different color planes and at several different focal planes. These images can be stitched together to form a two-dimensional or three-dimensional composite image. As a result of the combination, and because the images are typically in color and at high-resolution, the composite images place significant storage and bandwidth requirements on the medical imaging system. For example, a composite image for a single tissue slide can often exceed a gigabyte in size.
Image storage and archival devices provide a central library for storing the medical images captured by the image acquisition device. Image storage devices include one or more databases and image servers for fast access to recently acquired images. Archival devices, such as optical disc jukeboxes and tape backup systems, provide long-term storage. When a pathologist wishes to view an archived image, the image is automatically “migrated” from the corresponding archival device to one of the image storage devices.
Diagnostic quality view stations display the images captured by the image acquisition system. In order to assist the pathologist in interpreting a medical image, a view station is able to perform a variety of image processing operations on the medical image. For example, the pathologist at the view stations may invoke algorithms to perform densitometry on selected regions of the medical image in order to identify concentration of a particular analyte within the tissue sample. Other image processing operations are useful for finding objects within the image such as the nuclei of the cells, computing an integrated optical density for the nuclei of the cells and reporting the number of molecules per cell. Most image processing operations output a fixed number (score), often falling within a predetermined range.